IBM POWERPC 750GL - Manual (Page 259)

User’s Manual
IBM PowerPC 750GX and 750GL RISC Microprocessor
gx_07.fm.(1.2)
March 27, 2006 Signal Descriptions
Page 259 of 377
7.2.4.3 Transfer Burst (TBST)
The transfer burst (TBST) signal is an input/output signal on the 750GX.
Transfer Burst (TBST)—Output
Transfer Burst (TBST)—Input
Timing Assertion/
Negation/
High
Impedance The same as A[0–31].
Table 7-3. Data-Transfer Size
TBST TSIZ[0–2] Transfer Size
Asserted 010 Burst (32 bytes)
Negated 000 8 bytes
Negated 001 1 byte
Negated 010 2 bytes
Negated 011 3 bytes
Negated 100 4 bytes
Negated 101 5 bytes 1
Negated 110 6 bytes 1
Negated 111 7 bytes 1
1. Not generated by the 750GX.
State Asserted Indicates that a burst transfer is in progress.
Negated Indicates that a burst transfer is not in progress.
For external control instructions (eciwx and ecowx), TBST is used to output
bit 28 of the EAR, which is used to form the resource ID (TBST||TSIZ0–
TSIZ2).
Timing Assertion/
Negation/
High
Impedance The same as A[0–31].
State Asserted/
Negated Used when snooping for single-beat reads (read with no intent to cache).
Timing Assertion/
Negation The same as A[0–31].